Project Summary Stroke is the leading cause of long-term disability in the United States and the 5th leading cause of death. Recent evidence suggests that omega-3 (n-3) fatty acids (FAs) act as bioactive unsaturated lipids with pleiotropic effects, and show neuroprotective properties in animal models of stroke. We initially reported that n-3 FAs injected acutely as triglyceride (TG) emulsion provided neuroprotection after ischemic brain injury. These findings showed that n-3 TG emulsions, administered immediately after ischemic injury, led to long-term neurofunctional and histomorphological recovery of the brain. However, we recently observed far more robust neuroprotection when n-3 FAs are carried in a ?new? molecule, n-3 diglyceride (DG), and injected acutely as a DG lipid emulsion after ischemic brain injury. While substantial progress has been made in studying physical properties and metabolism of TG emulsions, there is a marked paucity of data on intravenous (i.v.) DG emulsions, especially n-3 DG emulsions. In this proposal, our major goals are: (a) to characterize n-3 DG emulsion physical-chemical properties, (b) to study n-3 DG pharmacokinetics as a novel and clinically feasible delivery strategy for rapidly enhancing the content of n-3 FAs in the brain, and (c) to demonstrate the superiority of n-3 DG over n-3 TG emulsions as acute treatment in ischemic stroke in adult rodent stroke models. These goals will be achieved through experiments in the following Specific Aims. Under Aim 1 we will characterize the physical-chemical properties of n-3 DG emulsions (enriched with DHA or EPA or DHA+EPA); in Aim 2 we will determine in vitro cell uptake mechanisms of n-3 DG emulsions; and in Aim 3 we will investigate the metabolic clearance of n-3 DG emulsions in vivo and explore how acute administration of n-3 DG emulsions enhances n- 3 FA bioavailability and neuroprotection after ischemic injury, using STAIR guidelines. Our findings will provide for the first time the underlying physical and functional rationales of why n-3 DG emulsions are more neuroprotective and effective than n-3 TGs. The clinical use of DG emulsions will offer an efficient and innovative intravenous modality for facilitating the delivery of n-3 FAs to the brain and for accelerating the modulation of neuroprotective pathways in ischemic stroke. ! ! !